Nonactivated 1,3-enynes react with cyanamides under gold(I)-catalyzed conditions. This divergent interplay proceeds as 4 + 2-bimolecular or 2 + 2 + 2-trimolecular cycloadditions and affords 2-aminopyridines, 1-aminoisoquinolines, and 2,4-diaminopyrimidines. The impact of catalytic systems and electronic/steric parameters on reaction selectivity was studied, and these findings enable directing the cycloaddition along the desired pathway. As a result, a new highly selective modular approach to valuable 2-aminopyridines was proposed. The further synthetic potential of this methodology was demonstrated through postmodifications, including functionalizations of both the heterocyclic backbone and amino substituents.
Karagodin et al. (Tue,) studied this question.